Explosive-actuated tools



Sept. 23, 1969 FIGI.

R. D WACKROW EXPLOSIVE-ACTUATED TOOLS Filed Nov. 21, 1966 FIG.2.

IN VE/V 70/? ROGER DAV/D WW ATTORNEYS United States Patent 3,468,466 EXPLOSIVE-ACTUATED TOOLS Roger David Wackrow, Redditch, England, assrgnor to The Birmingham Small Arms Company Limited, B11- mingham, England, a British company Filed Nov. 21, 1966, Ser. No. 595,682

Int. Cl. B25c 1/14 U.S. Cl. 227- 1 Claim ABSTRACT OF THE DISCLOSURE An explosive-actuated tool for driving anchor members into hard materials comprising a body having a movably mounted barrel receiving a slidable piston. A chamber is formed in the rearward end of the body and receives a rearward head portion of the piston. The firing piston has a terminal annular shoulder, with a bore in the body extending from the shoulder through the end of the body. A locking cap is releasably secured to the end of the body for axial movement relative to the body, with the cap supporting a cartridge loading insert slidably received within the bore. When the locking cap is displaced forwardly to fire the cartridge against the piston head, the rear face of the firing chamber is defined by the annular shoulder and the end face of the cartridge holding insert which, at the time of firing, lie substantially in a common plane.

This invention relates to explosive actuated tools for driving nails, stud pins and other members (hereinafter referred to as anchoring members) into hard materials. The present invention is more particularly concerned with exposive actuated tools of the kind having a body which consists of two parts, the two parts being releasably secured together in such a manner that the firing of the tool causes stresses on the means for securing the two parts together, due to the reactive force of the expanding gases acting on only one part of the body.

It is an object of the present invention to reduce the stresses on the securing means for the two parts.

According to the present invention an explosive actuated tool of the kind referred to has a firing chamber one end of which chamber comprises two separate portions, one portion being secured to one part of the tool and the other portion being secured to the other part of the tool.

Preferably the end of the firing chamber comprises an outer annulus which is secured to one part of the tool, and a centre portion which is secured to the other part of the tool.

By arranging the end of the firing chamber with two portions one connected to each part of the body of the tool, a proportion of the reactive force of the expanding gases is taken by each part of the body (depending on the areas of the two portions) and hence the stresses on the securing means are reduced. If the areas of the two portions are arranged in the same proportions as the masses of the two parts, the stresses in the securing means may be substantially eliminated, as the two parts will attempt to accelerate an equal rate.

Certain types of explosive actuated tool are fired by 3,468,466 Patented Sept. 23, 1969 striking the end of the tool with a hammer and with this type of tool the hammer is in contact with the tool at the instant of firing of the cartridge. Thus in considering the mass of that part of the body which is struck by the hammer, the mass of the hammer must be included.

An embodiment of the invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a tool constructed in accordance with the invention and FIG. 2 is an exterior view of the same tool.

The tool comprises a tubular body 1, open at both ends. A piston 17 is mounted in the body, the forward end 4 of the piston rod being supported by a resiliently mounted slidable guide tube 2 projecting from one end of the body. An end cap 12 is releasably connected to the other end of the body by means of opposed shoulders and recesses, so that part rotation of the end cap aligns the shoulders and recesses and allows the end cap to be removed.

The end cap is provided with a hardened steel insert 13 which is adapted to enter partly into a bore 30 formed in the body at the firing chamber 16. The insert 13 is provided with a chamber 14 to receive a cartridge.

The end of the insert 13 and a shoulder 20 formed in the firing chamber form the rear face of the firing chamber -6. The shoulder 20 and the end of the insert 13 are normally not in the same plane (see FIG. 1), as the end cap 12, is urged by spring means (not shown) away from the end of the body.

When the tool is struck with a hammer to fire the cartridge, the spring is compressed and the end of the insert 13 and the shoulder 20 align to form a flat face, the shoulder 20 constituting an outer annulus and the end of the insert 13 constituting an inner core.

When a cartridge is placed in the chamber, the end cap 12 and the body 1 are secured together, and with an anchoring member 11 inserted in the guide tube 2, the tool may be fired by pressing it against a wall or other member and striking the end cap with a hammer.

The force of the expanding gases drives the piston 17 along the guide tube 2, at the same time acting against the rear face of the firing chamber, said rear face comprising the core and annulus previously referred to. Both the body 1 and the end-cap 12 Wil thus attempt to move rearwardly. Since both the body and the end-cap try to move in the same direction the shear stress on the shoulders and recesses connecting the end-cap to the body may be substantially reduced. This may allow the weight of the tool to be reduced by use of less substantial securing means.

If all the recoil force were directed onto the core, that is if there Were no annulus surrounding the core, the end cap would be forced back. This would create stresses in the locking means as the end-cap would attempt to move relative to the body.

What I claim is:

1. An explosive-actuated tool for driving anchoring members into hard materials comprising a body, a barrel slidably mounted in said body and piston means slidable in said barrel, a firing chamber in said body adapted to be entered by said piston means, an annular shoulder in sai dbody bounding the rearward end of said chamber, a bore in said body intersecting said chamber at said shoulder and extending from said chamber through the end of locking cap mounting a cartridge holding insert which is 5 slidably received in said bore, whereby when said locking cap is axially displaced to fire a cartridge by contacting it against said piston, the rearward face of said firing chamber is defined by said annular shoulder and the end face of said cartridge holding insert which lie in a substantially 10 common plane.

4 References Cited UNITED STATES PATENTS 5/1961 Schenkel 227-9 9/ 1962 Bell et a] 22710 THERON E. CONDON, Primary Examiner E. F. DESMOND, Assistant Examiner US. Cl. X.R. 6026.1 

